It has been shown that nanocomposites of polymers and inorganic materials may exhibit optical properties that cannot be obtained with pure polymers alone. See references: Kyprianidou-Leodidou, T., Caseri, W., and Suter, U. W., J. Phys. Chem. 1994, v 98, pp 8992-8997; Weibel, M.; Caseri, W.; Suter, U. W.; Kiess, H.; Wehrli, E., Polym. Ado. Technol. 1991, v 2, p 75; Zimmermann, L.; Weibel, M.; Caseri, W.; Suter, U. W., J. Mater. Res. 1993, v 8, p 1742; and Zimmermann, L.; Weibel, M.; Caseri, W.; Suter, U. W.; Walther, P., Polym. Adv. Technol. 1993, v 4, p 1. For instance, the introduction of PbS in a polymer matrix can increase the refractive index to values of 2.5-3.0 at 632.8 nm rendering the nanocomposite suitable material for optical applications. It has also been shown that the refractive index in PbS-gelatin nanocomposites increases linearly with the PbS volume fraction in the experimentally available range 0-50% v/v PbS.
Colloidal semiconductor particles of different sizes can be produced by reactions that have been carried out under a variety of conditions such as in non-aqueous media (Steigerwald, M. L.; Alivisatos, A. P.; Gibson, J. M.; Harris, Kortan, R.; Muller, A. J.; Thayer, A. J.; Duncan, T. M.; Douglass, Brus, L. E., J. Chem. Phys. 1988, v110, p3046; and Fischer, C. H.; Henglein, A., J. Phys. Chem. 1989, v93, p5578), reversed micelle (Lianos, P.; Thomas, J. K., J. Colloid Interface Sci. 1986, 117 (2), p505; and Petit, C.; Lixon, P.; Pileni, M. F., J. Phys. Chem. 1990, v 94, p1598), vesicles (Watzke, H. J.; Fendler, J. H., J. Phys. Chem. 1987, v91, p854), Langmuir-Blodgett films (Peng, X.; Guan, S.; Chai, X.; Jiang, Y.; Li, T., J. Phys. Chem. 1992, v 96, p3170), polymers (Mahler, W., Inorg. Chem. 1988, v27, p435, and Gallardo, S.; Gutierez, M.; Henglein, A.; Janata, E. Eer. Bunsenges., Phys. Chem. 1989, v93, p1080), and porous crystalline zeolites (Wang, Y.; Herron, N. J., Phys. Chem. 1987, v91, p257). In aqueous media, stabilizing agents such as thiols are used to vary the particle size. Thiols terminate the growth of colloidal particles probably by attaching to the surface of the particles (Nosaka, Y.; Yamaguchi, K.; Miyama, H.; Hayashi, H., Chem. Lett. 1988, p605, Swayambunathan, V.; Hayes, D.; Schmidt, K. H.; Liao, Y. X.; Meisel, D., J. Am. Chem. Soc. 1990, v112, p 3831, and Nosaka, Y.; Ohta, N.; Fukuyama, T.; Fuji, N. J., Colloid Interface Sci. 1993, v155, p 23.
The art demonstrates a need for the present invention. Dispersion of semiconductor nanocrystals in polymers has found particular interest in optical studies due to their quantum confinement effects and size-dependent photo emission characteristics. Generally, nanocomposites of polymer and semiconductor nanocrystals have been accomplished via an aqueous dispersion process. The polymer itself acts as a steric stabilizer and renders the particles immobile. In most cases, additional surfactants are added to the process to enhance the stability of the dispersions. Although, the previous process produces nanocrystals below 10 nm size, it appears to be limited to water soluble polymers. Due to the growing demand for nanocomposite materials for optical applications using high performance polymers as the matrix, an in-situ method was needed for non-aqueous preparation of nanocomposites (e.g. lead sulfide nanocomposites).